Have an ammonia system shutting down due to a high liquid alarm in the surge drum. It is only there on startup, well for thfirst hour. Usually it gos out 2-4 times and I had to close the valve off to pump it out today to keep it going. Once it gets off it will run with no problems all day. It's a Frick screw on a blast freezer. The oil I don't think has been drained for a while. I had a look through some old service sheets and I know at the end of September a sample was took for testing but I can't find the results. Also a small shaft seal leak was repaired. At this time a diaphragm and orifice was replaced to a valve which seemed to solve the problem but it has returned in the last day or two. My own thought was a liquid line solenoid passing causing the drum to overfill, I thought if the problem was TX valve related it would happen not only on startup. I don't want to have to change a load of bits to get it runnning but it needs it's overhaul as the 40,000 hr is getting close. It's a single stage recirculation system if that helps. I can't find a liquid pump either although I had only a quick look at the high side components as the freezer room was out of bounds so maybe hot gas dump trap. I shall return tomorrow and have a better look, as I will be able to start and stop the plant with no one in there. The closest I got to the coolers was the header and TX valve on top......another opinion would be good..